Facultative Anaerobic Species Research Articles

Fitness factor genes conserved within the multi-species core genome of Gram-negative Enterobacterales species contribute to bacteremia pathogenesis.

There is a critical gap in knowledge about how Gram-negative bacterial pathogens, using survival strategies developed for other niches, cause lethal bacteremia. Facultative anaerobic species of the Enterobacterales order are the most common cause of Gram-negative bacteremia, including Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, and Enterobacter hormaechei. Bacteremia often leads to sepsis, a life-threatening organ dysfunction resulting from unregulated immune responses to infection. Despite a lack of specialization for this host environment, Gram-negative pathogens cause nearly half of bacteremia cases annually. Based on our existing Tn-Seq fitness factor data from a murine model of bacteremia combined with comparative genomics of the five Enterobacterales species above, we prioritized 18 conserved fitness genes or operons for further characterization. Mutants were constructed for all genes in all five species. Each mutant was used to cochallenge C57BL/6 mice via tail vein injection along with each respective wild-type strain to determine competitive indices for each fitness gene. Five fitness factor genes, when mutated, attenuated mutants in four or five species in the spleen and liver (tatC, ruvA, gmhB, wzxE, arcA). Five additional fitness factor genes or operons were validated as outcompeted by wild-type in three, four, or five bacterial species in the spleen (xerC, prc, apaGH, atpG, aroC). Overall, 17 of 18 fitness factor mutants were attenuated in at least one species in the spleen or liver. Together, these findings allow for the development of a model of bacteremia pathogenesis that may include future targets of therapy against bloodstream infections.

Uncovering the role of oxygen on organic carbon cycling: insights from a continuous culture study with a facultative anaerobic bacterioplankton species (Shewanella baltica)

Deoxygenation is tied to organic carbon (Corg) supply and utilization in marine systems. Under oxygen-depletion, bacteria maintain Corg respiration using alternative electron acceptors such as nitrate. Since anaerobic respiration’s energy yield is lower, Corg remineralization may be reduced and its residence time increased. We investigated the influence of oxygen and alternative electron acceptors’ availability on Corg cycling by heterotrophic bacteria during a continuous culture experiment with Shewanella baltica, a facultative anaerobic γ-Proteobacteria in the Baltic Sea. We tested six different oxygen levels, from suboxic (<5 µmol L-1) to fully oxic conditions, using a brackish (salinity=14 g L-1) media supplied with high (HighN) or low (LowN) inorganic nitrogen concentrations relative to glucose as labile Corg source. Our results show that suboxia limited DOC (glucose) uptake and cell growth only under LowN, while higher availability of alternative electron acceptors seemingly compensated oxygen limitation under HighN. N-loss was observed under suboxia in both nitrogen treatments. Under HighN, N-loss was highest and a C:N loss ratio of ~2.0 indicated that Corg was remineralized via denitrification. Under LowN, the C:N loss ratio under suboxia was higher (~5.5), suggesting the dominance of other anaerobic respiration pathways, such as dissimilatory nitrate reduction to ammonium (DNRA). Bacterial growth efficiency was independent of oxygen concentration but higher under LowN (34 ± 3.0%) than HighN (26 ± 1.6%). Oxygen concentration also affected dissolved organic matter (DOM) cycling. Under oxic conditions, the release of dissolved combined carbohydrates was enhanced, and the amino acid-based degradation index (DI) pointed to more diagenetically altered DOM. Our results suggest bacterial Corg uptake in low-oxygen systems dominated by S. baltica can be limited by oxygen but compensated by high nitrate availability. Hence, suboxia diminishes Corg remineralisation only when alternative electron acceptors are lacking. Under high nitrate:Corg supply, denitrification leads to a higher N:C loss ratio, potentially counteracting eutrophication in the long run. Low nitrate:Corg supply may favour other anaerobic respiration pathways like DNRA, which sustains labile nitrogen in the system, potentially intensifying the cycle of eutrophication. Going forward, it will be crucial to establish the validity of our findings for S. baltica in natural systems with diverse organic substrates and microbial consortia.

Non-significant influence between aerobic and anaerobic sample transport materials on gut (fecal) microbiota in healthy and fat-metabolic disorder Thai adults.

The appropriate sample handling for human fecal microbiota studies is essential to prevent changes in bacterial composition and quantities that could lead to misinterpretation of the data. This study firstly identified the potential effect of aerobic and anaerobic fecal sample collection and transport materials on microbiota and quantitative microbiota in healthy and fat-metabolic disorder Thai adults aged 23-43 years. We employed metagenomics followed by 16S rRNA gene sequencing and 16S rRNA gene qPCR, to analyze taxonomic composition, alpha diversity, beta diversity, bacterial quantification, Pearson's correlation with clinical factors for fat-metabolic disorder, and the microbial community and species potential metabolic functions. Our study successfully obtained microbiota results in percent and quantitative compositions. Each sample exhibited quality sequences with a >99% Good's coverage index, and a relatively plateau rarefaction curve. Alpha diversity indices showed no statistical difference in percent and quantitative microbiota OTU richness and evenness, between aerobic and anaerobic sample transport materials. Obligate and facultative anaerobic species were analyzed and no statistical difference was observed. Supportively, the beta diversity analysis by non-metric multidimensional scale (NMDS) constructed using various beta diversity coefficients showed resembling microbiota community structures between aerobic and anaerobic sample transport groups (P = 0.86). On the other hand, the beta diversity could distinguish microbiota community structures between healthy and fat-metabolic disorder groups (P = 0.02), along with Pearson's correlated clinical parameters (i.e., age, liver stiffness, GGT, BMI, and TC), the significantly associated bacterial species and their microbial metabolic functions. For example, genera such as Ruminococcus and Bifidobacterium in healthy human gut provide functions in metabolisms of cofactors and vitamins, biosynthesis of secondary metabolites against gut pathogens, energy metabolisms, digestive system, and carbohydrate metabolism. These microbial functional characteristics were also predicted as healthy individual biomarkers by LEfSe scores. In conclusion, this study demonstrated that aerobic sample collection and transport (<48 h) did not statistically affect the microbiota and quantitative microbiota analyses in alpha and beta diversity measurements. The study also showed that the short-term aerobic sample collection and transport still allowed fecal microbiota differentiation between healthy and fat-metabolic disorder subjects, similar to anaerobic sample collection and transport. The core microbiota were analyzed, and the findings were consistent. Moreover, the microbiota-related metabolic potentials and bacterial species biomarkers in healthy and fat-metabolic disorder were suggested with statistical bioinformatics (i.e., Bacteroides plebeius).

Metagenomic comparison of effects of mesophilic and thermophilic manure anaerobic digestion on antimicrobial resistance genes and mobile genetic elements

This study evaluated the long-term effects of mesophilic (MAD) and thermophilic (TAD) anaerobic digestion on the fate and evolution of antimicrobial resistance genes (ARGs) and mobile genetic elements (MGEs) in cattle manure following a metagenomic approach. The results indicated that MAD and TAD lowered ARG levels in fresh cattle manure by over 50 % and MGEs by over 65 %. However, no statistically significant difference was observed between the MAD and TAD processes in terms of their ability to reduce ARG and MGE. Co-occurrence analysis suggested facultative anaerobic species belonging to the Bacillota and Actinomycetota phyla as the primary potential hosts of ARGs and MGEs. Analyses of co-assembled contigs revealed the presence of transposon and toxin-antitoxin systems in close proximity to ARGs typically found in anaerobic digesters. The identification of these systems near ARGs is particularly significant, as it highlights a potential mechanism for the persistence and spread of ARGs in such environments. Overall, the results indicated that digested cattle manure (whether under mesophilic or thermophilic conditions) would pose a much lower risk of dissemination of antimicrobial resistance than untreated manures. Since TAD did not outperform MAD at reducing ARGs and MGEs, thermophilic temperatures may not be necessary to improve ARG reduction rates in cattle manure AD. These valuable insights could help develop strategies to reduce the dissemination of antibiotic resistance due to manure treatment and disposal.

Isolation and characterization of facultative anaerobes involved in canned food spoilage and examining the effect of different preservative

Spoilage of canned food is a major issue worldwide. The major cause of spoilage of food in cans is due to bacterial contamination as a result of mishandling, damage or improper packaging treatment. To avoid spoilage and increase the shelf-life of canned food, various food preservatives are used. However, it is ideal to use specific preservatives for specific foods. There is a need to check the types of the organisms causing the food spoilage and the preservatives that can be used against them. The current study focuses on the isolation of facultative anaerobic bacterial species which are specifically involved in spoilage of canned food items, their characterization and effectiveness of different food preservatives against them. For this propose samples were taken from expired peas, meat, and pineapple cans. Each sample was cultured on Acid agar, Mannitol salt agar, DTPB agar, and EMB agar. The bacterial colonies were purified and characterized morphologically and biochemically. The effectiveness of food preservatives such as ascorbic acid, sodium benzoate, sodium propionic acid and sodium nitrite was analyzed on the isolated strains. Selected isolates were identified through 16S rRNA gene sequencing. Facultative anaerobes belonging to the genera Leucobacter and Exiguobacterium were identified in the expired food cans. Among the tested food preservatives, ascorbic acid was proved highly effective as it inhibited the growth of these organisms. Facultative anaerobes plays an important role in canned food spoilage and by utilizing specific food preservatives these microbes can be minimized.

Facilitating effects of the reductive soil disinfestation process combined with Paenibacillus sp. amendment on soil health and physiological properties of Momordica charantia.

Reductive soil disinfestation (RSD) is an anaerobic and facultative anaerobic microbial-mediated soil management process. The extent of improvement of diseased soil properties by RSD relative to comparable healthy soil is, however, not well characterized. Importantly, how to promote the colonization efficiency of these facultative anaerobic functional species to ensure soil and plant health remain unknown. Here, Fusarium wilt-diseased soil of Momordica charantia grown under a plastic-shed field (PS-CK) was used to conduct molasses-RSD (MO-RSD) along with Paenibacillus sp. (a model of facultative anaerobic species) (MOPA-RSD) treatment, and the soil from a nearby open-air paddy field was considered comparable healthy soil (OA-CK). Both RSD treatments significantly improved the properties of PS-CK soil, and the extent of improvement of soil pH, Fusarium oxysporum reduction efficiency (98.36%~99.56%), and microbial community and functional composition were higher than that achieved for OA-CK soil, which indicated that RSD-regulated most soil properties outperformed those of the comparable healthy soil. The disease incidence and ascorbic acid content of M. charantia in MO-RSD- and MOPA-RSD-treated soils were considerably decreased, while the weight and soluble protein contents were correspondingly increased, as compared to those of M. charantia in PS-CK soil. Specifically, the changes in these physiological properties of M. charantia in MOPA-RSD soil performed well than that in MO-RSD soil. The relative abundances of Cohnella, Effusibacillus, Rummeliibacillus, Oxobacter, Thermicanus, and Penicillium enriched in both RSD-treated soils were positively correlated with Paenibacillus and negatively correlated with F. oxysporum population and disease incidence (P < 0.05). Notably, the relative abundances of these potential probiotics were considerably higher in MOPA-RSD-treated soil than in MO-RSD alone-treated soil. These results show that the RSD process with inoculation of Paenibacillus sp. could promote the colonization of this species and simultaneously stimulate the proliferation of other probiotic consortia to further enhance soil health and plant disease resistance.

Analysis of the level of optopedical rehabilitation in studying the microbiome and evaluation of the degree of fixation of removable plated prosthesis.

The widespread use of traditional removable prosthetics is explained by the relative simplicity of the technological stages of manufacture and determines its availability. The development of prosthetic stomatitis of the oral cavity is facilitated by poor fixation and stabilization of removable orthopedic structures. Microbiome biofilms formed on the surface of dental orthopedic structures can help reduce their service life and cause an inflammatory process of the oral cavity of microbial etiology during dental prosthetics in the process of orthopedic rehabilitation. The purpose of the study: to assess the level of adaptation of patients during orthopedic rehabilitation based on the study of the microbiome and the assessment of the degree of fixation of removable lamellar dentures. Qualitative and quantitative characteristics of the microbiome of prostheses at the stages of orthopedic pealitation were assessed; facultative anaerobic species belonging to the genera Staphylococcus, Micrococcus, Enterococcus, Streptococcus, Klebsiella prevailed;noted the elimination of microorganisms of the genera Bifidobacterium and Lactobacterium, yeast-like fungi of the species Candida albicans were isolated. An analysis of the index of fixation of prostheses showed an increase depending on the duration of use; a good level of fixation of prostheses was established in groups of patients.

Supercharged MPNs? Automated Determination of High-Throughput Most Probable Number (htMPN) Using Chip-Based 3D Digital PCR.

Surface plating on agar and most probable number (MPN) are the standard methods for determining bacterial viability but both have limitations. Here we present a novel cell count method, high-throughput MPN (htMPN), that uses a chip-based digital PCR instrument to accelerate and to improve the quantification of viable or sublethally injured cells. This method tracks growth of up to 20,000 individual bacterial cells on a single chip. Single cells were grown in the individual wells of the chip at their optimal temperature until the cell density was high enough to detect the fluorescent signal with cell-permeant or cell-impermeant DNA-intercalating fluorescent dyes. This method based on microfluidic devices implemented in digital PCR equipment was equivalent to surface plating in determining cell counts of Escherichia coli, Salmonella enterica serovar Typhimurium, Fructilactobacillus sanfranciscensis, Pseudomonas putida, and vegetative cells but not spores of Bacillus subtilis. Viable E. coli could be enumerated within 7 h. Culture of strict aerobes was restricted to strains that are capable of nitrate respiration; organisms requiring complex media that also contain double-stranded DNA were detected after treatment of growth media with DNase before inoculation. Our approach not only monitors the frequency distribution of bacterial growth and determines cell counts with high reliability but also detected heat-injured cells of S. Typhimurium that escaped detection by the surface plating. Overall, the method accelerates detection of viable bacterial cells, facilitates automation, and offers new possibilities for the analysis of individual bacterial cells. IMPORTANCE htMPN uses chip-based fluorescence acquisition and is a simple and compact tool for automatic viable cell enumeration with applications in microbiological research. This method applies to a wide range of anaerobic or facultative anaerobic species and improves accuracy by reducing the number of pipetting steps. In addition, the method offers an additional tool for single-cell microbiology. The single cell time-to-detection times have been used as an important criterion for the physiological state of bacterial cells after sublethal stress, and htMPNs support the acquisition of such data with an unprecedented number of cells. In particular, htMPN provides an anaerobic environment and enables a long incubation time to increase the recovery rate of sublethally injured cells. Given its reproducibility and reliability, our approach can potentially be applied to quantify viable cells in samples from environmental, clinical, or food samples to reduce the risk of underestimation of the number of viable bacterial cells.

The Numerical Simulation of the rivalry between aerobic and anaerobic bacteria species in a chemostat model

We investigate a chemostat model that contains interaction between two bacteria species, the aerobic species, and a facultative anaerobic species. The competition is restricted on the dissolved oxygen where the aerobic species consumes the oxygen for growth, on the other hand, the facultative anaerobic species do not need the dissolved oxygen for growth. We found that the aerobic growth rate is more extensive compared to that of its competition, the anaerobic species. During our study of the chemostat system, we found three equilibria solutions. The first one is found at the initial dissolved oxygen concentration with the condition of both species washed out. The second equilibrium point is seen when both the dissolved oxygen and the aerobic species present, and finally, the third equilibrium point is found when the dissolved oxygen and the facultative anaerobic species present. We used MATLAB software to simulate these aforementioned three equilibria.

Diversity of Vaginal Microbiome in Pregnancy: Deciphering the Obscurity.

Human microbiota plays an indispensable role in physiology, nutrition and most significantly, in imparting immunity. The role of microbiota has remained cryptic for years, until recently meticulous studies revealed the interaction and dynamics of these microbial communities. This diversified state is governed by hormonal, behavioral and physio-chemical changes in the genital tract. Many inclusive studies have revealed “Lactobacillus” to be the most dominant member of vaginal flora in most of the healthy, reproductive age group and pregnant females. A total of five community state types have been described, out of which four are dominated by Lactobacillus while the fifth one by facultative or strict anaerobic species. A variation between species stability and gestational age has also been revealed. Studies have divulged a significant higher stability of vaginal microbiota in early stages of pregnancy and the same increased subsequently. Inter-species and racial variation has shown women belonging to White, Asian, and Caucasian race to harbor more of the anaerobic flora. The vaginal microbiome in pregnancy play a significant role in preterm and spontaneous labor. This Lactobacillus-rich microbiome falls tremendously, becoming more diverse in post-partum period. Apart from these known bacterial communities in human vagina, other microbial communities have also been traced. The major fragment is constituted by vaginal viral virome and very little information exists in relation to vaginal mycobiome. Studies have revealed the abundance of ds DNA viruses in vaginal microbiome, followed by ssDNA, and few unidentified viruses. The eukaryotic viruses detected were very few, with Herpesvirales, and Papillomaviridae being the only pathogenic ones. This flora is transmitted to infants either via maternal gut, vagina or breast milk. Recent studies have given an insight for vaginal microbiome, dissociating the old concept of “healthy” and “diseased.” However, more extensive studies are required to study evolution of virome and mycobiome in relation to their association with bacterial communities; to establish and decode full array of vaginal virome under the influence of genotypic and environmental factors, using novel bioinformatic, multi-omic, statistical model, and CRISPR/Cas approaches.

Staphylococcus saccharolyticus: An Overlooked Human Skin Colonizer.

Coagulase-negative staphylococcal species constitute an important part of the human skin microbiota. In particular, facultative anaerobic species such as Staphylococcus epidermidis and Staphylococcus capitis can be found on the skin of virtually every human being. Here, we applied a culture-independent amplicon sequencing approach to identify staphylococcal species on the skin of healthy human individuals. While S. epidermidis and S. capitis were found as primary residents of back skin, surprisingly, the third most abundant member was Staphylococcus saccharolyticus, a relatively unstudied species. A search of skin metagenomic datasets detected sequences identical to the genome of S. saccharolyticus in diverse skin sites, including the back, forehead, and elbow pit. Although described as a slow-growing anaerobic species, a re-evaluation of its growth behavior showed that S. saccharolyticus can grow under oxic conditions, and, in particular, in a CO2-rich atmosphere. We argue here that S. saccharolyticus was largely overlooked in previous culture-dependent and -independent studies, due to its requirement for fastidious growth conditions and the lack of reference genome sequences, respectively. Future studies are needed to unravel the microbiology and host-interacting properties of S. saccharolyticus and its role as a prevalent skin colonizer.

Single-channel properties, sugar specificity, and role of chitoporin in adaptive survival of Vibrio cholerae type strain O1

Vibrio cholerae is a Gram-negative, facultative anaerobic bacterial species that causes serious disease and can grow on various carbon sources, including chitin polysaccharides. In saltwater, its attachment to chitin surfaces not only serves as the initial step of nutrient recruitment but is also a crucial mechanism underlying cholera epidemics. In this study, we report the first characterization of a chitooligosaccharide-specific chitoporin, VcChiP, from the cell envelope of the V. cholerae type strain O1. We modeled the structure of VcChiP, revealing a trimeric cylinder that forms single channels in phospholipid bilayers. The membrane-reconstituted VcChiP channel was highly dynamic and voltage induced. Substate openings O1', O2', and O3', between the fully open states O1, O2, and O3, were polarity selective, with nonohmic conductance profiles. Results of liposome-swelling assays suggested that VcChiP can transport monosaccharides, as well as chitooligosaccharides, but not other oligosaccharides. Of note, an outer-membrane porin (omp)-deficient strain of Escherichia coli expressing heterologous VcChiP could grow on M9 minimal medium supplemented with small chitooligosaccharides. These results support a crucial role of chitoporin in the adaptive survival of bacteria on chitinous nutrients. Our findings also suggest a promising means of vaccine development based on surface-exposed outer-membrane proteins and the design of novel anticholera agents based on chitooligosaccharide-mimicking analogs.

Tumor-Targeting Bacteria: As Vectors, Immunotherapeutic Agents And Tumor-Targeting Probes For Cancer Detection And Therapy

Cancer is the world's second leading cause of death in humans. Conventional anticancer therapies are often associated with lack of tumor specificity, failure to detect small metastases, increased resistance of tumors to anticancer drugs, and unintended adverse effects. Numerous alternative and better strategies in cancer treatment have been developed to overcome the negative effects of traditional cancer therapies. More than a century ago, William Coley, the father of cancer immounotherapy, laid the groundwork for bacterial anticancer therapy. Bacterial immunotherapy has been emerging as a potential anticancer therapy. Moreover, certain obligate and facultative anaerobic bacterial species are exploited as vectors for gene delivery to treat cancer. These genes encode for anticancer agents, cytokines, cytotoxic peptides, anti-angiogenic proteins, therapeutic molecules and prodrug-converting enzymes. Genetically engineered bacterial strains of Salmonella, Bifidobacterium, Clostridium and Listeria are widely used to deliver genes in anticancer therapy since they can selectively accumulate in solid tumors with a hypoxic/necrotic core in vivo, providing appealing delivery systems to target therapeutic agents and immunomodulatory molecules to the site of tumor. Certain genetically modified bacterial species such as Bifidobacterium longum and Bacillus licheniformis have been effectively used for the enzyme/prodrug therapy for cancer. Furthermore, certain anaerobic bacteria are emerging as potential tumor markers due to the increased mobility and the selectivity in germinating and multiplying in hypoxic/anoxic environments. Many of these novel developments have been studied extensively in different experimental models of cancer and certain clinical trials are ongoing for some treatment modalities. Although favourable results have shown so far, further studies and technological innovations are required to ensure the efficacy of bacterial anticancer therapy.

Osmunda japonica Extract Suppresses Pro-Inflammatory Cytokines by Downregulating NF-κB Activation in Periodontal Ligament Fibroblasts Infected with Oral Pathogenic Bacteria.

Periodontal diseases are caused by bacterial infection and may progress to chronic dental disease; severe inflammation may result in bone loss. Therefore, it is necessary to prevent bacterial infection or control inflammation. Periodontal ligament fibroblasts (PDLFs) are responsible for the maintenance of tissue integrity and immune and inflammatory events in periodontal diseases. The formation of bacterial complexes by Fusobacterium nucleatum and Porphyromonas gingivalis is crucial in the pathogenesis of periodontal disease. F. nucleatum is a facultative anaerobic species, considered to be a key mediator of dental plaque maturation and aggregation of other oral bacteria. P. gingivalis is an obligate anaerobic species that induces gingival inflammation by secreting virulence factors. In this study, we investigated whether Osmunda japonica extract exerted anti-inflammatory effects in primary PDLFs stimulated by oral pathogens. PDLFs were stimulated with F. nucleatum or P. gingivalis. We showed that pro-inflammatory cytokine (IL-6 and IL-8) expression was induced by LPS or bacterial infection but decreased by treatment with O. japonica extract following bacterial infection. We found that the activation of NF-κB, a transcription factor for pro-inflammatory cytokines, was modulated by O. japonica extract. Thus, O. japonica extract has immunomodulatory activity that can be harnessed to control inflammation.

Microbial community profiles grown on 1020 carbon steel surfaces in seawater-isolated microcosm

Corrosion of metallic alloys is a concern worldwide, with impacts affecting different production sectors and consequent economic losses in the order of billions of dollars annually. Biocorrosion is a form of corrosion where the participation of microorganisms can induce, accelerate, or inhibit corrosive processes. In this study, it was evaluated that the changes in profile communities, by the sequencing of the 16S ribosomal gene, grown over steel coupons in a microcosm with no additional oxygen supplementation for 120 days. Analysis of abundance and diversity indices indicates marked changes in microbial structures throughout the 120-day period. Homology results of OTUs generated by Illumina sequencing indicated Proteobacteria phylum as the dominant group, comprising about 85.3% of the total OTUs, followed by Firmicutes and Bacteriodetes, both with 7.35%. Analyses at lower taxonomic levels suggested the presence of representatives described as corroders, such as Citreicella thiooxidans, Thalassospira sp., and Limnobacter thiooxidans. In conclusion, the results suggest that no additional oxygen supplementation profoundly altered the core of microbial communities, with a predominance of facultative anaerobic species.

Enhanced textile wastewater treatment by a novel biofilm carrier with adsorbed nutrients

Abstract This work aimed to enhance the biodegradation of synthetic textile wastewater using pyrolyzed sludge from an effluent treatment plant of a textile industry as biofilm carrier. The control carrier was compared to a carrier supplemented with nutrients (potassium, phosphorus, nitrogen, calcium, and sulfur) that were sequentially adsorbed. These nutrients are essential for microbial metabolism. First, the decolorization of the azo dye Reactive Red 141 (RR141) was tested and then, the biodegradation of synthetic textile wastewater was analyzed. The microorganisms present in each condition were identified by mass spectrometry. The supplemented carrier enhanced RR141 decolorization 3.6-fold and 1.8-fold when compared to free biomass and control carrier, respectively. The dye biodegradation followed a pseudo-second-order kinetics. The use of the supplemented carrier increased the rate constant 4.3-fold and 13.8-fold in relation to the use of control carrier and free biomass, respectively. For the synthetic textile wastewater, the supplemented carrier enhanced the decolorization 2.9-fold and 1.6-fold compared to free biomass and control carrier, respectively. The decolorization also followed pseudo-second-order kinetics, and there were increases of 8.8-fold and 3.5-fold in the rate constant with the use of the supplemented carrier in relation to free biomass and control carrier, respectively. Biofilm microorganisms were identified by mass spectrometry, which showed the presence of aerobic (Lysinibaciullus fusiformis for example) and facultative anaerobic (Escherichia coli and Kosakonia cowanii) species. The supplementation of the biofilm carrier with nutrients can be an interesting alternative for the effective treatment of more complex effluents, such as textile wastewater.

Review on Pathogenic Bacteria Listeria monocytogenes, The Detection and The Sequencing Gene Methods Isolated from Meat Products

A study was conducted to review on pathogenic bacteria Listeria monocytogenes, the detection and the sequencing gene methods isolated from meat products, compare selected methods that detect the presence of Listeria monocytogenes in selected raw and processed meat products. Results indicate that Listeria monocytogenenes (originally named Bacterium monocytogenes) is a gram-positive, non-sporeforming, highly mobile, rod-type, and facultative anaerobic bacterium species. It can grow under temperatures between -1.5°C to 45°C and at pH range between 4.4 and 9.4, with the optimum pH of 7. Rapid methods (PCR based and VIDAS-LDUO®) detected Listeria monocytogenes faster than the conventional method. It was also gathered that Phenotypic identification and Genotypic identification are two types of confirmation test for Listeria monocytogenes. Listeria monocytogenenes can be found in raw meat and meat product because of environmental contamination, cross contamination or error process.

Evolution and Functional Analysis of orf1 Within nif Gene Cluster from Paenibacillus graminis RSA19.

Paenibacillus is a genus of Gram-positive, facultative anaerobic and endospore-forming bacteria. Genomic sequence analysis has revealed that a compact nif (nitrogen fixation) gene cluster comprising 9–10 genes nifBHDKENX(orf1)hesAnifV is conserved in diazotrophic Paenibacillus species. The evolution and function of the orf1 gene within the nif gene cluster of Paenibacillus species is unknown. In this study, a careful comparison analysis of the compositions of the nif gene clusters from various diazotrophs revealed that orf1 located downstream of nifENX was identified in anaerobic Clostridium ultunense, the facultative anaerobic Paenibacillus species and aerobic diazotrophs (e.g., Azotobacter vinelandii and Azospirillum brasilense). The predicted amino acid sequences encoded by the orf1 gene, part of the nif gene cluster nifBHDKENXorf1hesAnifV in Paenibacillus graminis RSA19, showed 60–90% identity with those of the orf1 genes located downstream of nifENX from different diazotrophic Paenibacillus species, but shared no significant identity with those of the orf1 genes from different taxa of diazotrophic organisms. Transcriptional analysis showed that the orf1 gene was expressed under nitrogen fixation conditions from the promoter located upstream from nifB. Mutational analysis suggested that the orf1 gene functions in nitrogen fixation in the presence of a high concentration of O2.

Studies on occurrence, characterisation and decontamination of emerging pathogenic Escherichia coli (STEC, ETEC and EIEC) in table eggs

ABSTRACT1. Escherichia coli is one of the most common facultative anaerobic species present in the gastrointestinal tract of animals and human beings. Usually they occur as commensals, but some serotypes can cause significant illnesses in humans as well as mammals and birds.2. The occurrence of E. coli in different categories of table eggs collected from markets was evaluated. Isolates were analysed for the presence of virulence genes, antibiotic susceptibility pattern and efficacy of peracetic acid and chlorine for the purpose of decontaminating table eggs.3. Significant differences were observed in the occurrence of E. coli between different groups viz. processed (cleaned, washed, sanitised and packed eggs), unprocessed (un-cleaned, un-sanitised and loose eggs) and free range (eggs obtained from backyard poultry) table eggs. Overall, E. coli occurred in table eggs at 28.6% with 22.9, 29.2 and 50.0% occurrence in processed, unprocessed and free-range table eggs, respectively.4. A total of 24 isolates of E. coli were obtained and screened for virulence genes viz. STH, SLT1/2 and INVE genes. Of the 24 isolates recovered, 10 typeable isolates belonged to O141, O119, O9, O120 and O101 serotypes, while the remaining 14 were untypeable. Antibiograms of the isolates showed multiple antimicrobial resistance (MAR) index in the range of 0.13–0.40.5. Peracetic acid (PAA) and chlorine (CL) were studied for their sanitisation efficacy; concentrations of 100 mg/kg of PAA and 200 mg/kg of CL completely inactivated E. coli over the egg surface and also resulted in 2.58 and 2.38 log reduction in total viable counts (TVC), respectively.6. The presence of virulence-associated shiga-like toxin (SLT1/2) and invasion E (INVE) genes and antimicrobial resistance among the emerging serotypes of pathogenic E. coli isolated from table eggs has public health implications. It underscores the need to implement better management practices across the production systems and marketing channels to produce E. coli-free wholesome eggs for consumers.

NOX1/2 activation in human gingival fibroblasts by Fusobacterium nucleatum facilitates attachment of Porphyromonas gingivalis.

Periodontal diseases are infectious polymicrobial inflammatory diseases that lead to destruction of the periodontal ligament, gingiva, and alveolar bone. Sequential colonization of a broad range of bacteria, including Fusobacterium nucleatum and Porphyromonas gingivalis, is an important phenomenon in this disease model. F. nucleatum is a facultative anaerobic species thought to be a key mediator of dental plaque maturation due to its extensive coaggregation with other oral bacteria, while P. gingivalis is an obligate anaerobic species that induces gingival inflammation by secreting various virulence factors. The formation of a bacterial complex by these two species is central to the pathogenesis of periodontal disease. Reactive oxygen species (ROS) are produced during bacterial infections and are involved in intracellular signaling. However, the impact of oral bacteria-induced ROS on the ecology of F. nucleatum and P. gingivalis has yet to be clarified. In the present study, we investigated ROS production induced in primary human oral cells by F. nucleatum and P. gingivalis and its effect on the formation of their bacterial complexes and further host cell apoptosis. We found that in primary human gingival fibroblasts (GFs), two NADPH oxidase isoforms, NOX1 and NOX2, were activated in response to F. nucleatum infection but not P. gingivalis infection. Accordingly, increased NADPH oxidase activity and production of superoxide anion were observed in GFs after F. nucleatum infection, but not after P. gingivalis infection. Interestingly, in NOX1, NOX2, or NOX1/NOX2 knockdown cells, the number of P. gingivalis decreased when the cells were coinfected with F. nucleatum. A similar pattern of host cell apoptosis was observed. This implies that F. nucleatum contributes to attachment of P. gingivalis by triggering activation of NADPH oxidase in host cells, which may provide an environment more favorable to strict anaerobic bacteria and have a subsequent effect on apoptosis of host cells.